This exploratory/developmental (R21) application is a two-year research project designed to develop and test a brief motivational intervention (BMI) for reducing alcohol and other drug (AOD) problems in a multicultural sample of adolescent girls. Female adolescents' AOD use is a pressing and increasing public health concern. However, few controlled studies have evaluated, specifically with females, the efficacy of behavioral AOD treatments. This lack of relevant efficacy data is a major limitation in evaluating behavioral treatments for girls and women. To address this limitation, this application proposes to conduct an initial evaluation of a BMI designed to reduce adolescent AOD problems, Guided Self Change (GSC), with an adolescent female population. GSC is a treatment with demonstrated effectiveness in reducing AOD problems in male youth. Clinical trial participants in the current study will consist of a diverse sample of at risk female students (ages 14 to 18) attending alternative high schools in Miami. Participants (N= 164) will be randomly assigned to two conditions: (1) GSC or (2) no-treatment control. Treatment will consist of 5 weekly individual sessions. Participants in the GSC condition will be assessed before and after the treatment and at 3- and 6-month follow-up intervals. Control group participants will be assessed at parallel intervals. The results of this exploratory/developmental study will help build a solid evidence base for the efficacy of BMIs in reducing AOD problems among girls, and for GSC as a specific BMI treatment for girls. The proposed study will also permit an exploration of gender-linked factors in treatment-relevant subgroups of girls (e.g., those with a history of maltreatment, partner violence, trauma symptoms, and psychiatric symptoms) for whom brief motivational treatment may be least effective. Key features of the study include a manualized treatment, theory-driven hypotheses, a randomized controlled trial design, and an ethnically/racially diverse sample of girls with AOD problems. The data collected during this study will provide the basis for rigorous evaluation of girls' response to GSC treatment in a future R01 application. Future evaluation efforts may also focus on determining the effectiveness of multiple versions of this GSC treatment, tailored to the needs of specific subgroups of girls.